Starting a fuel-injected internal combustion engine in a very cold state, such as under arctic conditions, proves to be very difficult in practice. If such a start is carried out without any assistance such as pre-heating the internal combustion engine or a special additive in the fuel, one must expect extremely long start times when temperatures are very low.
For example, German Patent No. 26 25 095 describes opening and closing exhaust-gas flaps in an exhaust pipe of an internal combustion engine manually via an exhaust-brake valve to thus prevent an excessive exhaust-gas pressure in front of the exhaust-gas flaps.
Furthermore, German Patent No. DE-GM 73 01 889 describes a device for controlling exhaust-gas flaps in which the flaps are closed during a cold start of the engine to prevent the formation of white smoke, and are opened again automatically via a time switch after a predetermined time has elapsed. This device is only designed for controlling the exhaust-gas flaps after a cold start of the engine. A similar device is also described in German Patent No. 33 39 053.
The described devices involve a control of the exhaust-gas flaps to suppress white smoke, i.e., the exhaust-gas flaps are actuated in connection with the actual operation of the internal combustion engine.
An object of the present invention is to provide a method with which combustion chambers of a fuel-injected internal combustion engine can be heated in a simple manner.
According to the present invention, a very simple and inexpensive method is provided for heating the combustion chambers of a fuel-injected internal combustion engine which can replace or supplement previously known measures such as pre-heating the combustion chambers or special fuel additives.
Using the measure of the present inventionxe2x80x94retaining the exhaust-gas flap in the closed state during a specific period of time after switching on the ignition of the motor vehiclexe2x80x94prevents a fresh air supply (i.e., the feeding of extremely cold air in arctic conditions), while at the same time the engine is driven via the starter, as a result of which the air present in the combustion chambers (cylinders) of the internal combustion engine is compressed and therefore heated.
It is preferred that the predeterminable time during which the exhaust-gas flap is closed be definable taking into account a state of charge of a battery allocated to the internal combustion engine. This measure allows the method of the present invention to be adapted optimally to a state of charge of a battery so that, for example, when working with a fully charged battery, the start operation can be considerably shortened compared to conventional start operations.